The invention relates to a signal processing device for the execution of processes, a first process of which produces a data token with a process identification and a plurality of data items whereas a second process processes the data items of the first process, which signal processing device includes:
a first processing element which executes the first process and successively produces the data items, and PA1 a second processing element which, in response to the reception of the data token, processes the plurality of data items according to the second process under the control of the process identification. PA1 sequence programming means for programming a process sequence of a number of programmably selected processes; PA1 sequencing means for imposing a restriction as regards a transmission sequence in which the processes transmit data tokens via the communication connection in conformity with the process sequence of processes programmed in the sequence programming means. Thus, during the programming of the signal processing device the programmer or the compiler can take steps in order to prevent deadlock and starvation, for example by specifying that the processes supplying inputs for different processes allocated to one and the same processing elements are alternately started.
A signal processing device of this kind is known from an article by Bang W. Lee et al. in Proceedings of the IEEE 1994 Custom Integrated Circuits Conference (CICC; San Diego, May 1994) pp. 103-106: "Data Flow Processor for Multi-standard Video Codec".
Notably video signal processing requires processing speeds which, given the IC technique at present, can be achieved only by parallel processing in a number of processing elements. The scheduling of the parallel processing conventionally utilizes a control flow architecture with centrally coordinated program control in which the scheduling of the various parallel processes performed on data items is defined.
The article by Bang W. Lee proposes to schedule the parallel processes according to a data flow principle. According to the data flow principle, use is made of units of data, referred to as data tokens, which are processed according to various processes. Each data token contains not only conventional data items, but also a process identification wherefrom the process to be performed on the data items can be deduced. The processor starts the process in response to the availability of the data token to be processed, the process being chosen on the basis of the process identification, without a centrally coordinated program control determining in advance which process is to be stared at which instant.